Organic siloxane copolymer film, method and deposition apparatus for producing same, and semiconductor device using such copolymer film

ABSTRACT

An insulated organic copolymer is provided, having the excellent mechanical strength and deposition property at an interface contacting the lower base or the upper layer of the inorganic insulation film, and the effective dielectric constant is low as the whole film, which is suitable as the interlayer insulation film that separates the multi-layer copper wirings of the semiconductor device. The organosiloxane copolymer film is obtained by the polymerization of the cyclosiloxane and the straight-chain siloxane as the raw materials by the plasma excitation of both. At the interfaces contacting the inorganic insulation films, the interface layers having a film quality that is intricate and excellent in deposition property are prepared whereby the main component of the film composition is the straight-chain siloxane. The inner section of the copolymer film mixes the cyclosiloxane component having pores surrounded by the cyclosiloxane backbone and the straight-chain siloxane components, has the network structure layer relatively suppressing the density, and has the composition changing in the thickness direction whereby the multi-layer wirings embedding the copper thin film is formed.

FIELD OF THE INVENTION

The present invention relates to an organosiloxane copolymer film usedas an organic insulation film for insulating between wirings thatconnect between elements within a semiconductor device, its productionmethod, its deposition apparatus, and a semiconductor device using thecopolymer film. More specifically, the present invention relates to avapor-deposited organosiloxane copolymer film and a vapor depositionmethod of the copolymer film conforming to the application to thesemiconductor devices.

BACKGROUND OF THE INVENTION

The design rule of a semiconductor integrated circuit is continuouslybeing shrinked, accompanied by the performance deterioration due towiring delay which is becoming prominent. That is, a wiring signal delayof a semiconductor integrated circuit is determined by a wiring CR timeconstant (C: wiring capacity, R: wiring resistance). Because of theincrease in wiring resistance due to the decrease in a wire width andthe increase in a capacity due to the decrease in a gap between wires,there is a danger that the wiring CR time constant may not catch up withthe improvement in switching speed of transistors. Conventionally, analuminum alloy was mainly used as a wiring material of a semiconductorintegrated circuit. However, a copper wiring has been used in anintegrated circuit requiring high-speed operation for a purpose ofdecreasing the resistance in a wiring.

In order to reduce the capacitance between wirings, an insulation filmmaterial that has a lower dielectric constant than the currently usedsilica (SiO₂) is beginning to be adopted. As an insulation film having alow dielectric constant, a fluorine-containing silica (SiOF), a poroussilica, and an organic polymer film (organic insulation film) are known.The fluorine-containing silica is already being used in part of someproducts, however, if the fluorine concentration inside the film isincreased for promoting a low dielectric constant of the film itself,the problem of corrosion of a wiring metal occurs with hydrofluoric acidgenerated from a reaction with moisture or hydrogen, or the problem ofthe increased dielectric constant occurs by desorption of fluorine.Furthermore, as the technology of the semiconductor integrated circuitprogresses, the fluorine-containing silica film (SiOf) providing thedielectric constant of 3.3 can no longer meet the requirement of theinsulation film. The insulation film that does not contain fluorine andhas the dielectric constant of 3 or less is in high demand as theinterlayer insulation film of the multi-layer wirings. As one of thecandidates, the organosiloxane copolymer film having excellentproperties both in heat and moisture resistance has been in urgentdemand for development. Conventionally reported methods of forming theorganosiloxane copolymers are broadly classified to the spin coatingmethod and the CVD method.

1. First Related Art

In the spin coating method, a raw material organosiloxane monomer isdissolved in an organic solvent. The spin-coated film is formed, thesolvent is removed during the film formation, the organosiloxane monomerinside the coated film is heated, and a polymerization reaction of themonomer proceeds. Consequently, a two-dimensional or three-dimensionalnetwork structure polymer film is formed by the thermal polymerizationreaction. A backbone configuring the organosiloxane copolymer film whichis the product, depends on the structure of the organosiloxane monomerdissolved in the organic solvent.

For example, according to “REAL-TIME FT-IR STUDIES OF THE REACTIONKINETICS FOR THE POLYMERIZATION OF DIVINYL SILOXANE BIS BENZOCYCLOBUTENE MONOMERS” (material Research Symposium Proceeding vol, 227, p,103, 1991), by T. M. Stokich, Jr., W. M. Lec, and R. A. Peters disclosesthe method of forming an organosiloxane polymer film. After dissolving adivinylsiloxane-bisbenzocyclobutene (BCB-DVS) monomer which is one typeof the straight-chain siloxane in a mesitylene which is spincoated, themesitylene in the solvent is removed by baking at 100 degrees Celsius,and the residue was further heated up to 300 degrees Celsius to 350degrees Celsius to obtain the organosiloxane polymer film. Adivinylsiloxane-bisbenzocyclobutene monomer, as shown in chemicalformula (1) below, is an organosiloxane monomer that includes 2 vinylgroups and 2 cyclobutene groups which are unsaturated hydrocarbonchains, and the straight-chain siloxane. Its thermal polymerizationreaction is progressed as follows.

Chemical Formula (1): divinylsiloxane-bisbenzocyclobutene

First of all, accompanied by the reaction of chemical formula (2) shownbelow, the cyclobutene group inside thedivinylsiloxane-bisbenzocyclobutene monomer undergoes thermalring-opening polymerization reaction by thermal energy, and changes to 2vinyl groups (methylene groups).

Chemical Formula (2): Ring-Opening Reaction of Benzocyclobutene Group

Accompanied by the reaction of chemical formula (3) shown below, 2 vinylgroups (methylene groups) react to another vinyl group inside theBSB-DVS monomer to form the 6-membered hydrocarbon (dihydronaphthalene)so that the polymerization reaction is generated. From this reactionpath, a dimer that connects 2 BSB-DVD shown in chemical formula (4)below, is obtained.

Chemical Formula (3): Addition Polymerization Reaction of Vinyl Groupand Open-Ring Group of Benzocyclobutene Group.

Chemical formula (4): divinylsiloxane-bisbenzocyclobutene Dimer

Inside the dimer of BCB-DVS to bc synthesized, 3 unreactedbenzocyclobutenes and 3 vinyl groups remain. That is, at least 6 BCB-DVSmonomers and the dimer may further undergo addition polymerization. If amobility of the divinylsiloxane-bisbenzocyclobutene is sufficientlylarge, then a complex and intricate polymer film where the BSB-DVS arebridged to one another is formed as shown in chemical formula (5).

Chemical Formula (5): Organic Polymer Film Synthesized by AdditionPolymerization of divinylsiloxane-bisbenzocyclobutene (BSB-DVS)

However, as for the polymer formation by using the spin coating method,a BSB-DVS monomer is being dissolved in a solvent, but, if the monomerconcentration increases accompanied by the evaporation of the solvent,the viscosity is increased, and the monomer mobility gets less. In otherwords, although there are total of 4 sites available for additionpolymerization in the BSB-DVS monomer itself, it can only bond to a fewBSB-DVD nearby. Because of this, the polymer formation by using the spincoating method cannot attain a sufficient bridge density. Incidentally,there was a problem of deterioration in thermal resistance of theobtained polymer film, and a problem of decline in the film strength.Furthermore, the spin coating method in this case dissolves the organicmonomer to a solvent, and the dissolved solid is spin coated. However,the spin coating process has a drawback that the yield of the startingraw material is low because about 90% of the dissolved material isscattered from the substrate. Moreover, the method of heating aspin-coated film in a baking furnace thereby to remove a solventbeforehand, and further heated at high temperature to cause thepolymerization reaction of the organic monomer thereby forming anorganic polymer film. At this time, when oxygen is present in the bakingfurnace, the organic polymer film having the desired characteristics isnot obtained sometimes by the reaction of oxygen with a portion of theorganic monomer. To prevent that from happening, for example, theatmosphere in the whole baking furnace is effectively replaced by anitrogen gas, however, it is difficult to realize that at a low cost.Furthermore, since the dissolved oxygen in the solvent had sometimesreacted with the organic monomer during baking, a strict atmospherecontrol is required throughout the whole process, but it is practicallydifficult to carry out the strict atmosphere control in the spin coatingmethod. Although the spin coating is conducted in a locally evacuatedspin coating chamber to prevent scattering of the volatile solvent inthe working environment, there is also a risk of contamination of thespin-coated film with floating dust particles or fine particles of thedried organic monomer adhered to the inner wall of the spin coatingchamber. In this case, the film quality is deteriorated. Furthermore,the spin coating also has a problem that the environmental burden islarge because a large amount of organic solvent is required and theamount of evaporation is also large.

(Second Prior Art)

Japanese unexamined patent publication No, HEI 11-288931 discloses aplasma CVD method using as a raw material a single vaporized gas whichis the silicon type hydrocarbon compound where the saturated hydrocarbonis bonded to the straight-chain siloxane (—Si—O—Si—), for obtaining thesilicon type organic insulation film with the dielectric constant of 3or less. By adjusting the FR power or the deposition pressure during theplasma polymerization, although the composition ratio of elements suchas carbon, hydrogen, silica and oxygen inside the synthesizedorganosiloxane film can be controlled, however, the molecular backbonestructure of the obtained organosiloxane film or the polymerizationstructure of the whole film cannot be controlled.

(Third Prior Art)

Published Japanese translations of PCT international publication forpatent application No. 2002-503879 (hereinafter referred to asliterature 3) discloses a technique to form the organosiloxane film byreacting the oxidized gas eliminated by using a low-powered plasma withthe organosilicone compound monomer (organosiloxane monomer) composed ofthe saturated hydrocarbon group and the siloxane. This reaction processdoes not have the polymerization selectivity such as activating aspecific hydrocarbon group in the organosiloxane monomer and bonding toa specific site and an oxidizing agent gas. Accordingly, when oxidizingthe organosiloxane monomer inside the plasma, it was difficult tostrictly control its oxidation reaction or its degree of oxidation. Inother words, it was difficult to design molecules of porous film byinducing minute pores to the silicone type organic insulation film.Furthermore, in order to improve the deposition property of the siliconeorganic insulation film synthesized as the lower and upper layers, itwas necessary to control the composition of organosiloxane film near tothe interface. According to the disclosed organosiloxane film formationmethod, it does not have the means for controlling the molecularstructure or the chemical composition of the intermediate layer or thecomposition near to the interface. The present inventors have developedthe technology to form the organosiloxane film on the substrate surfaceby vaporizing the organosiloxane monomer including an unsaturatedhydrocarbon group, transporting it through the vapor using a carriergas, and spraying to the heated substrate surface via the He plasmaformed in the reaction chamber. This relating technology is disclosed inJapanese unexamined patent publication No. HEI 2000-12532. According tothis organosiloxane film formation method, a vapor-transportedorganoxiloxane monomer generates the polymerization reaction on thesubstrate surface, and the organosiloxane film is formed. For example,if divinylsiloxane-bisbenzocyclobutene (BCB-DVS) monomer is utilizedshown in chemical formula (1), having the straight-chain organosiloxaneas backbone, its plasma polymerization reaction process is assumed tocoincide approximately to the thermal polymerization reaction, and thecyclobutene group and the vinyl group which are the unsaturatedhydrocarbon groups included in the organosiloxene are selectivelyactivated, and the organosiloxane film having an intricate bridgestructure shown in the chemical formula (5) is obtained, by thepolymerization reaction via the elementary reaction processes shown inthe chemical formulae (2) to (4).

The key point of this technology is in the fact that the unsaturatedhydrocarbon group such as cyclobutene group or vinyl group is includedin the organosiloxene monomer used as a raw material, and theorganosiloxene monomers are bonded in a network shape via theseunsaturated hydrocarbon groups. In other words, by controlling theposition of the unsaturated hydrocarbon groups taking part in thepolymerization reaction, the position of the polymerization reaction isspecified, and a network structure of the desired organosiloxane filmwith organosiloxane monomer backbone is formed. Since the organosiloxanemonomer supplied as a vapor is in high vacuum, in comparison to the spincoating method, its mobility is large on the surface, and the filmstrength and the thermal resistance of the obtained organosiloxane filmare increased by improving the bridge density of the network structure.For example, as for the organosiloxane film obtained from the BCB-DVSmonomer by the plasma polymerization, it has a highly dense bridgestructure of the straight-chain siloxanes via the unsaturatedhydrocarbon, and its dielectric constant is ranging from 2.5 to 2.7.

Particularly, in the case of using it as the interlayer insulation filmof the multi-layered wiring of ULSI, the organosiloxane film structureis formed in between the upper wiring layer and lower electrode layer.At this time, other insulation film is used in the production of thelower electrode layer and the upper wiring layer. Accordingly, theorganosiloxene film of the interlayer insulation film is of a laminatedstructure with the organic or inorganic insulation film of the upperlayer and lower layer. Because of this, it is necessary that the filmstrength and the deposition property of the insulation film at theinterface contacting the upper plane or the lower plane of theorganosiloxane film to be high. To improve the film strength near to theinterface or the deposition property of the organosiloxane film, it iseffective to increase its bridge density but that accompanies theincrease in the dielectric constant.

Ideally, the organosiloxene film utilized as the interlayer insulationfilm, has a high strength film quality and a high bridge density whichis excellent in the deposition property only near to the interface withother film material. Other section of the interlayer other than theinterface ideally has a film configuration that keeps a bridge densitythat can attain the appropriate dielectric constant. However, as for theplasma polymerization film utilizing the single organosiloxene monomeras the raw material, it was generally difficult to arbitrarily selectthe bridge density of the obtained polymer film in the film thicknessdirection to make the polymer film with the continuously changingdeposition property and dielectric constant. That is, in the plasmapolymer film using the conventional single raw material, it wasimpossible to arbitrarily control the bridge density for controlling thefilm quality to a large extent and continuously in the film thicknessdirection.

DISCLOSURE OF INVENTION

The present invention solves the previously mentioned problems.Accordingly, an objective of the present invention is to provide a neworganosiloxane polymer film capable of arbitrarily controlling a filmstructure section keeping a bridge density that can attain anappropriate dielectric constant, and a section indicating the highstrength film quality and the high bridge density that is excellent inthe deposition property, capable of changing the bridge structure insidethe film continuously and yet to a large extent, in the film thicknessdirection, and which is suitable for use as the insulation interlayerfilm.

Furthermore, an another objective of the present invention is to providea production method of the new organosiloxane polymer film capable ofarbitrarily controlling a film structure region section keeping a bridgedensity that can attain an appropriate dielectric constant, and asection indicating the high strength film quality and the high bridgedensity that is excellent in the deposition property, capable ofchanging the bridge structure inside the film continuously and yet to alarge extent, in the film thickness direction, and which is suitable foruse as the insulation interlayer film.

In more specific terms, the aim of the present invention is to providean organosiloxane polymer film that selected 2 or more organosiloxaneraw materials for readily achieving the capability of arbitrarilycontrolling a film structure section keeping a bridge density that canattain the appropriate dielectric constant, and a section indicating thehigh strength film quality and the the high bridge density which isexcellent in the deposition property, capable of changing the bridgestructure inside the film continuously and yet to a large extent, in thefilm thickness direction, when providing the organosiloxane copolymerfilm by the plasma polymerization method using 2 or more organosiloxaneraw materials.

Furthermore, the aim of the present invention is to provide a productionmethod of the organosiloxane polymer film that selected 2 or moreorganosiloxane raw materials, for readily achieving the capability ofarbitrarily controlling a film structure section keeping a bridgedensity that can attain the appropriate dielectric constant, and asection indicating high strength film quality and the high bridgedensity that is excellent in the deposition property, capable ofchanging the bridge structure inside the film continuously and yet to alarge extent, in the film thickness direction, when providing theorganosiloxane copolymer film by the plasma polymerization method using2 or more organosiloxane raw materials.

Furthermore, the aim of the present invention is to provide a productionapparatus of the organosiloxane polymer film that selected 2 or moreorganosiloxane raw materials for readily achieving the capability ofarbitrarily controlling a film structure section keeping a bridgedensity that can attain the appropriate dielectric constant, and asection indicating the high strength film quality and the high bridgedensity that is excellent in the deposition property, capable ofchanging the bridge structure inside the film continuously and yet to alarge extent, in the film thickness direction, when providing theorganosiloxane copolymer film by the plasma polymerization method using2 or more organosiloxane raw materials.

Furthermore, the aim of the present invention is to provide asemiconductor device which utilizes the organosiloxane polymer film asthe interlayer insulation film that selected 2 or more organosiloxaneraw materials, for readily achieving the capability of arbitrarilycontrolling a film structure section keeping a bridge density that canattain the appropriate dielectric constant, and a section indicatinghigh strength film quality and the high bridge density that is excellentin the deposition property, capable of changing the bridge structureinside the film continuously and yet to a large extent, in the filmthickness direction, when providing the organosiloxane copolymer film bythe plasma polymerization method using 2 or more organosiloxane rawmaterials.

The inventors found that the polymer film that utilized only theorganosiloxane with straight-chain siloxane as raw materials for theplasma polymerization attains a high bridge density, a high strengthfilm quality, a high surface density of siloxane structure, and anexcellence in the deposition property to the other material film.Furthermore, the inventors recognized that the copolymer film is formedwhich maintains the cyclosiloxane structure by implementing the plasmapolymerization adding the organosiloxane with straight-chain siloxanebackbone is added to the organosiloxane with cyclosiloxane backbone,accompanied by an increase in the ratio of the organosiloxane withcyclosiloxane backbone, accompanied by a decrease in the average densityof the film, and accompanied by the fact of attaining a reduction in thedielectric constant. In addition to the acquired knowledge, theinventors recognized that since the organosiloxane with cyclosiloxanebackbone and the organosiloxane with straight-chain siloxane backboneare vaporized and supplied as vapors, therefore, their ratio cancontinuously be changed, as well as the quality of the obtainedcopolymer film can continuously be changed. The inventors completed thepresent invention accordingly.

In other words, the organosiloxane copolymer film according to thepresent invention, wherein the organosiloxane copolymer film with pluralkinds of organosiloxanes as the configuration units, wherein the pluralkinds of organosiloxanes derived configuration units include at least afirst organosiloxane with cyclosiloxane backbone, and a secondorganosilxoane with straight-chain siloxane backbone, wherein theorganosiloxane copolymer film forms a bridge structure by bonding aplurality of the second organosiloxanes to the first organosiloxane. Atthis time, the organosiloxane copolymer film preferably has a filmconfiguration thereby a content ratio of the first organosiloxane withcyclosiloxane backbone derived unit and the second organosiloxane withstraight-chain siloxane backbone derived unit is changing, in thethickness direction.

Furthermore, the organosilxoane copolymer film configures a formationwhereby the upper and lower planes in the thickness direction are bothcontacting the inorganic insulation films. The organosiloxane copolymerfilm having a content ratio of the first organosiloxane derived unit andthe second organosiloxane derived unit, wherein the secondorganosiloxane with straight-chain siloxane backbone derived unit is themain component, near to the interface with the inorganic insulation filmof the upper and lower planes, and wherein the content ratio with thesecond organosiloxane derived unit is lower than that of the interfaceat the film inner section. The density near to the interface is largerthan the density in the film inner section.

In addition to that, the present invention provides a semiconductordevice invention as the preferred usage of the previously-describedorganosiloxane copolymer film. In other words, the semiconductor deviceaccording to the present invention is a semiconductor device utilizingthe organosiloxane film as the interlayer insulation film, wherein theorganosiloxane film is an organosiloxane copolymer film having theplural kinds of organosiloxanes as configuration units, wherein theorganosiloxane film includes at least including a first organosiloxanewith cyclosiloxane backbone and a second organosiloxane withstraight-chain backbone, thereby forming a bridge structure by bondingthe plurality of second organosiloxanes to the first organosiloxane,wherein the organosiloxane copolymer film is sandwiched by the inorganicinsulation films. The content ratio of the first organosiloxane derivedunit and the second organosiloxane derived unit near to the interfaces,of the inorganic insulation films at the upper and lower planes, themain component is the second organosiloxane with straight-chain backbonederived unit, and the content ratio with the second organosiloxanederived unit is lower than that of the interface at an film innersection. A density near to the interface is larger than a density at thefilm inner section. The organosiloxane copolymer film forms a wiringlayer embedding a copper film therein.

Now, the present invention further provides the production methodsuitable in producing the previously-described organosiloxane copolymerfilm according to the present invention. In other words, a vapordeposition method of the organosiloxane copolymer film of the presentinvention is a method of growing the organosiloxane copolymer film onthe substrate surface, having the plural kinds of organosiloxanes asconfiguration units. The organosiloxane copolymer film at least includesa first organosiloxane with cyclosiloxane backbone and a secondorganosiloxane with straight-chain siloxane backbone as the plural kindsof organosiloxane configuration units. The copolymer film is forming abridge structure by bonding a plurality of the second organosiloxanes tothe first organosiloxane. The copolymer film at least has a step ofvaporizing a first organosiloxane monomer with cyclosiloxane backbone, astep of vaporizing a second organosiloxane monomer with straight-chainsiloxane backbone, a step of supplying the vaporized firstorganosiloxane monomer gas at the pre-determined supply rate, a step ofsupplying the vaporized second organosiloxane monomer gas at thepre-determined supply rate, a step of mixing the supplied firstorganosiloxane monomer gas and the supplied second organosiloxanemonomer gas to form a mixed gas, a step of inducing the mixed gas to adepressurized reaction chamber, and a step of spraying onto the heatedsubstrate after passing the mixed gas induced through the plasmaatmosphere formed in the reaction chamber. The vapor deposition methodof the organosiloxane copolymer film grows a copolymer film forming abridge structure by reacting first organosiloxane monomer and the secondorganosiloxane monomer in the mixed gas sprayed on the substrate, and bybonding the plurality of second organosiloxanes to the firstorganosiloxane.

At this time, the supply rate of the first organosiloxane monomer gasand the supply rate of the second organosiloxane monomer gas arerespectively changed so as to change their supply rate ratio.Accompanied by the change in supply rate ratio, the film configurationpreferably has a changing content ratios of the first organosiloxanewith cyclosiloxane backbone derived unit and the second organosiloxanewith straight-chain siloxane backbone derived unit, in the thicknessdirection.

On the other hand, an apparatus suitable for implementing the vapordeposition method of the organosiloxane copolymer film according to thepresent invention is also provided. In other words, the vapor depositionapparatus for the organosiloxane copolymer film according to the presentinvention is a vapor deposition apparatus of the organosiloxanecopolymer film having the plural kinds of organosiloxanes asconfiguration units, at least comprises: monomer gas supplying units forcontrolling the supply amounts of the plural kinds of organosiloxanemonomer gases and supplying them separately; a cleaning gas supplyingunit; a mechanism for forming a mixed gas by mixing the monomer gasessupplicd from the monomer gas supplying units and a cleaning gassupplied from the cleaning gas supplying unit as required; a reactionchamber equipping a substrate heating section capable of loading asubstrate, and a shower head capable of spraying the mixed gas uniformlyto a substrate plane loaded on the substrate heating section; a RF powersupply connected to the shower head for applying the RF voltage to theshower head, in respect to the earthed substrate heating section; and anexhaust apparatus for depressurizing inside the reaction chamber;wherein the monomer gas supplying units at least is provided with afirst monomer supplying unit for vaporizing and supplying the firstorganosiloxane with cyclosiloxane backbone, and a second monomersupplying unit for vaporizing and supplying the second organosiloxanewith straight-chain siloxane backbone.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic drawing showing an addition polymerizationreaction processing of the first organosiloxane with cyclosiloxanebackbone and the second organosiloxane with straight-chain siloxanebackbone for configuring the organosiloxane copolymer film of thepresent invention, and one example of the network structure formationprocessing inside the copolymer film.

FIG. 2 is a schematic drawing showing one example of a straight-chainsiloxane derived bridge structure, added to the network structure of thecopolymer film, upon increasing the content ratio of the second siloxanewith straight-chain siloxane backbone against the first organosiloxanewith cyclosiloxane backbone, and a high density of the whole copolymerfilm, for the organosiloxane copolymer film according to the presentinvention.

FIG. 3 is a schematic drawing showing a configuration example of a vapordeposition apparatus utilizing the plasma excitation mechanism,equipping two kinds of independent organosiloxane monomer vaporsupplying systems, utilized in the production of organosiloxanecopolymer film according to the present invention.

FIG. 4 is a schematic drawing showing a configuration of vaporizationcontroller using the liquid flow control mechanism applicable tovaporizing and supplying the liquid organosiloxane monomer at the roomtemperature.

FIG. 5 is a schematic drawing showing a configuration of vaporizationsupplying system applicable to vaporizing and supplying the solidorganosiloxane monomer at the room temperature, by using thevaporization controller and the vaporization flow control mechanism.

FIG. 6 is a schematic drawing showing the polymerization reaction usingthe plasma excitation, for producing the organosiloxane copolymer filmas one embodiment of the present invention, by using the BCBDVS monomergas which is a straight-chain siloxane, and by using the TVTMCTS monomergas which is a cyclosiloxane.

FIG. 7 is a schematic drawing showing an example of the formationprocess of organosiloxane copolymer film according to the presentinvention, and the formation of network structure by polymerizationreaction of cyclosiloxane and straight-chain siloxane, accompanied bythe selective plasma excitation.

FIG. 8 is a schematic drawing showing an example of the formation pathof the organosiloxane copolymer film according to the present invention,and shows the network structure formation by the polymerization reactionof the cyclosiloxane and the straight-chain siloxane accompanied by theselective plasma excitation, and shows the bridge formation after thestraight-chain siloxane interaction.

FIG. 9 is a schematic drawing showing an example of the formationprocessing of the organosiloxane copolymer film according to the presentinvention, and shows the network structure formation by thepolymerization reaction of the cyclosiloxane and the straight-chainsiloxane accompanied by the selective plasma excitation, and shows the2-dimensional bridge structure formation after the straight-chainsiloxane interaction.

FIG. 10 is a schematic drawing showing a structure of the organosiloxanecopolymer film according to the present invention having a compositionmodulation in the thickness direction, preferably used as the interlayerinsulation film in the semiconductor device.

FIG. 11 is a schematic drawing showing an example of the organosiloxanecopolymer film according to the present invention, particularly, thecomposition modulation type organosiloxane copolymer film utilized as awiring insulation film whereby the multi-layer wiring structure isconfigured on the semiconductor device.

FIG. 12 is a schematic drawing showing the polymerization reaction usingthe plasma excitation in forming the organosiloxane copolymer film whichis one embodiment of the present invention by using the divinylsiloxanesgroup shown in general formula (12) as the straight-chain siloxane andthe 3-membered cyclosiloxanes groups shown in general formula (11) asthe cyclosiloxane.

FIG. 13 is a schematic drawing showing a formation of the hexagonallattice network structure by the polymerization reaction of thedivinylsiloxane group and the 3-membered siloxane group, accompanied bythe selective plasma excitation which is an example of the formationprocessing of the organosiloxane copolymer film.

BEST MODE TO CARRYING OUT THE INVENTION

Hereunder, the present invention shall be described in detail.

The organosiloxane copolymer film of the present invention has pluralkinds of organosiloxanes as configuration units. The configuration unitsderived from plural kinds of organosiloxanes, includes at least a firstorganosiloxane with cyclosiloxane backbone and a second organosiloxanewith straight-chain siloxane backbone. The first organosiloxane withcyclosiloxane backbone uses a structure which is substituted byunsaturated hydrocarbon groups, capable of addition polymerizationreaction, as the cyclosiloxane backbone. On the other hand, the secondorganosiloxane with straight-chain siloxane backbone uses a structurewhich is substituted by at least more than 2 unsaturated hydrocarbon,capable of addition polymerization reaction, as the straight-chainsiloxane backbone.

FIG. 1 shows an addition polymerization reaction processing of the firstorganosiloxane with cyclosiloxane backbone and the second organosiloxanewith straight-chain siloxane backbone for configuring the organosiloxanecopolymer film, and one example of the network structure formationprocessing inside the copolymer film. As schematically shown in FIG. 1,the addition polymerization reaction is carried out to the firstorganosiloxane and the second organosiloxane. For every one of the firstorganosiloxane with cyclosiloxane backbone, the second organosiloxanewith straight-chain siloxane backbone not only react in plural numbersbut also forms a copolymer with the first organosiloxane withcyclosiloxane backbone since it possess more than 2 unsaturatedhydrocarbon groups, by connecting between two of the firstorganosiloxane with cyclosiloxane backbone. At this time, the bridgestructure is formed by a plurality of second organosiloxanes withstraight-chain siloxane backbone reacting to a single firstorganosiloxane with cyclosiloxane backbone. The copolymer film as awhole can configure a bridge structure that is stretched in a networkshape.

In addition to that, the bridge structure can be formed from just thesecond organosiloxane with straight-chain siloxane backbone. That is, astructure of at least 3 substituted unsaturated hydrocarbon groups andmore, capable of addition polymerization reaction is used as thestraight-chain siloxane backbone, then the bridge formation is possiblefurther by the addition polymerization of the second organosiloxane inbetween the second organosiloxane with straight-chain siloxane backboneconnecting the two first organosiloxane with cyclosiloxane backbone.FIG. 2 shows one example of a straight-chain siloxane derived bridgestructure, added to the network structure of the copolymer film, uponincreasing the content ratio of the second siloxane with straight-chainsiloxane backbone against the first organosiloxane with cyclosiloxanebackbone, and a high density of the whole copolymer film, for theorganosiloxane copolymer film. In other words, as schematicallyillustrated in FIG. 2, in addition to the large network shape bridgestructure centering the first organosiloxane with cyclosiloxanebackbone, an intricate bridge structure between the secondorganosiloxane with straight-chain siloxane backbone is furtherattached, so that the whole network structure is markedly intricate.

In other words, if the content ratio of the second organosiloxane withstraight-chain siloxane backbone increases, the obtained copolymer filmbecomes high in the bridge density, has a high-strength film quality,and has an excellent deposition property. On the other hand, if thecontent ratio of the second organoxiloxane with straight-chain siloxanebackbone is relatively low, the bridge density gets relatively low, andmoreover, the siloxane unit contained per unit volume is relativelysuppressed, as a result, the dielectric constant itself is kept low. Inaddition to that, the pores derived from the cyclosiloxane backbone havea role of suppressing an elevation of the bulk density, whichcontributes to reduction in the dielectric constant. Now, the size ofpores derived from the cyclosiloxane backbone is dependent on the numberof membered rings of the cyclosiloxane. In addition to that, the ratioof unit numbers derived from the first organosiloxane with cyclosiluxanebackbone and the second organosiloxane with straight-chain siloxanebackbone are dependent on the supply ratios from a vapor phase to thesubstrate surface. Being dependent on the mixture ratio inside the mixedgas, the film quality of the obtained copolymer film can continuously bechanged by changing the mixture ratio inside the mixed gas during itsgrowth.

The content ratio of straight-chain siloxane unit and cyclosiloxane unitin the copolymer film is, for example, can be evaluated, based on arelative ratio of both infrared ray adsorption intensities, using adifference in the molecular vibration caused by the straight-chainsiloxane backbone and the cyclosiloxane backbone. In specific terms, afrequency derived from a stretch motion of the 4-membered cyclosiloxaneis 1085 cm⁻¹, a frequency derived from the stretch motion of the3-membered cyclosiloxane is 1015 cm⁻¹, on the other hand, a frequencyderived from the stretch motion of the straight-chain siloxane is 1055cm⁻¹. Their adsorption peaks are classifiable and detectable by usingthe FT-IR method.

The first organosiloxane with cyclosiloxane backbone which is used in aconfiguration of the organosiloxane copolymer film according to thepresent invention, it has at least 2 or more sites where the additionpolymerization reaction is possible for configuring the copolymer, andfurthermore, preferably it has at least 3 or more sites where theaddition polymerization reaction is possible for configuring the largenetwork bridge structure as its core. On the other hand, the secondorganosiloxane with straight-chain siloxane backbone has at least 2 ormore sites where the addition polymerization reaction is possible forconfiguring the copolymer, and furthermore, preferably it has at least 3or more sites where the addition polymerization reaction is possible forconfiguring an intricate bridge structure of the second organosiloxanewith straight-chain siloxane backbone interconnections.

Hereinbelow, the process of forming the organoxiloxane copolymer filmaccording to the present invention as described above and the apparatusutilized in its growth shall be explained. FIG. 3 shows a configurationexample of a vapor deposition apparatus utilizing the plasma excitationmechanism, equipping two kinds of independent organosiloxane monomervapor supplying systems, utilized in the production of theorganosiloxane copolymer film.

First of all, a reaction chamber 1 is depressurized by a vacuum pump 8,a substrate heating section 6 is prepared inside the reaction chamber 1,and a semiconductor substrate 5 is fixed on top of it. The firstorganosiloxane monomer (organic monomer A) and the second organoxiloxanemonomer (organic monomer B) are in vaporized states inside the vaporizedsupplying systems 61 and 62, respectively. The monomers are supplied andmixed immediately before the reaction chamber 1, via the raw materialsupply pipings 38A and 38B, and via valves 18A and 18B, together with acarrier gas. After mixing the two, it is guided to the reaction chamber1. Being vaporized at the vaporized supply systems 61 and 62, the firstorganosiloxane monomer 22A and the second organoxiloxane monomer 22Bthat are diluted by the carrier gas, respectively, and they are suppliedto a shower head 7, at the same time, supplied to the reaction chamber 1through the vaporized raw material supply piping 49 equipped with aheater 3 for maintaining the piping temperature. The vaporized anddiluted monomers are dispersed and sprayed on a substrate surface of thesemiconductor substrate 5 at the uniformly mixed state. At this time, aRF power was applied to the shower head 7, thereby to generate a plasmabetween the space of the substrate heating section 6 and the shower head7. The first organosiloxane monomer (organic monomer A) and the secondorganosiloxane monomer (organic monomer B) pass through the plasma. Bythe excitation energy derived from the plasma, and by a thermal energysupplied from the substrate heating section 6, the copolymerizationreaction of the first organosiloxane monomer 22A and the secondorganoxiloxane monomer 22B is generated, and the organosiloxanecopolymer film 4 is grown on the surface of the semiconductor substrate5.

Now, the unreacted raw material monomer heats an inner wall of thereaction chamber 1 and the vacuum pump 8 keeps the reduced pressureinside the reaction chamber 1. This way, without causing cohesion on theinner wall of the reaction chamber 1, the unreacted monomer as a vaporreaches to a cooling trap 14 via the exhaust gas piping 16 heated by aheater. Inside the cooling trap 14, the first organosiloxane monomer andthe second organosiloxane monomer are both cooled, as a result, theirvapor pressures exceed the saturated vapor pressure, and are liquefiedor solidified in the cooling trap 14. In the cooling trap 14, as aresult of effective elimination and recycling, the unnecessaryorganosiloxane monomer reaching a lower flow of the exhaust pump 8 isprevented from happening. Besides, a vapor flow controller 13 and avalve 17 are prepared to supply a cleaning gas 21 for cleaning thereaction chamber 1

FIG. 4 shows schematically one example of the organosiloxane monomer rawmaterial supplying system applicable to its vaporizing and supplying inthe case of the first organosiloxane monomer, and the secondorganosiloxane monomer used in the present invention are liquid at theroom temperature. The system shown in FIG. 4 illustrates the process ofvaporized monomer at a vaporization controller, and the supplyingprocess immediately before the reaction chamber. First, the firstorganic monomer A22 as liquefied is supplied from the firstorganosiloxane monomer tank 23A to a vaporization controller A 30A, viaa valve 46, a liquid flow indicator A28A, and a valve 43. At this time,it is supplied to a vaporization controller A 30A via a vaporizationcontrol valve A 35A and a valve 37 inside a vaporization controller A,which is feedback controlled from the first organosiloxane monomerliquid flow indicator 28A. On the other hand, a carrier gas A 26A issupplied to the vaporization controller 30A through a valve 45A.Henceforth, immediately before a vaporization chamber A 32A, the firstorganosiloxane monomer 22A which is a liquid and a carrier gas A 26A aremixed. In a mixed state with the carrier gas A, the liquid raw materialmonomer A 22A supplied to the vaporization chamber A 32A receives asudden pressure decline upon being supplied to the vaporization chamber32A, at the same time, it is continuously vaporized due to a thermalenergy being supplied by a heater 34A. The vaporized firstorganosiloxane monomer is supplied to the reaction chamber 1 via the rawmaterial supply piping 38A and a valve 18A. As for the secondorganosiloxane monomer, likewise, in the case of being liquid at theroom temperature, a various organosiloxane monomer raw materialsupplying systems can be used.

FIG. 5 shows schematically one example of the organosiloxane monomer rawmateial supplying system applicable to its vaporizing and supplying, inthe case of the first organosiloxane monomer and the secondorganosiloxane monomer utilized in the present invention are solid atthe room temperature. The system shown in FIG. 5 indicates the processfrom a vaporization process inside the organosiloxane monomer tank 23Bto the supplying process immediately before the reaction chamber 1. Aflow amount of a carrier gas B 26B is controlled in the vapor flowcontroller 31B, and supplied to an organic monomer B tank B23B via avalve 45B. At this time, the organosiloxane monomer B tank 231B isheated to a certain temperature. The heating temperature is selected tothe temperature for obtaining a sufficient saturted vapor pressure byvaporizing the organic monomer B from the melt state, alternatively, bysublimating from the solid state. At this time, the carrier gas B 26Bbecomes a state of including the vaporized organosiloxane monomer B atthe saturated vapor pressure. After that, if the temperature isdecreased, cohesion of the organic monomer B included occurs, and beyondthe valve 46B, the vapor flow indicator B 33B and a valve 43B are heatedto the same temperature and more, and are controlled to maintain thesublimation state or the vaporized state. The carrier gas is supplied,and then the vaporized organosiloxane monomer B is supplied to the rawmaterial supply piping 38B via the valve 46B, the vapor flow indicator B33B, and a valve 433. Then, it is supplied to the reaction chamber 1 viathe valve 41B.

As described above, by selecting an appropriate supplying system,regardless of the organosiloxane monomer raw material being a liquid ora solid at the room temperature, the organosiloane monomer under thevaporized state can be supplied to the reaction chamber at the desiredsupply ratio. Now, in the case of using the organosiloxane monomer gasat the room temperature, beforehand, after diluting with the carriergas, the supply amount is controlled by the gas flow controller. At thistime, to avoid the temperature decline of the mixed gas upon mixing withother organosiloxane monomer, the raw material supply piping 36B isdesirably heated by a heater 3. Moreover, as a carrier gas utilized inthe present invention is appropriately and ideally an inert gas such ashelium gas, argon gas, and neon gas, in respect to the organosiloxanemonomer. Moreover, the ideal carrier gas as such is ideally a gas thatcontributes to the maintenance of the plasma generated inside thereaction chamber 1.

In other words, the organosiloxane monomers inherent an unsaturatedhydrocarbon group as a site capable of the addition polymerizationreaction, wherein the unsaturated hydrocarbon group is activated by thecollision of low energy electron inside the plasma, and theorganosiloxane copolymer film having the uniform inner planedistribution of the cyclosiloxane and the straight-chain siloxane isgrown by spraying to the heated substrate, and by the additionpolymerization between the unsaturated hydrocarbon groups while swiftlymoving the substrate surface. In more specific terms, even in the caseof possessing a difference which is significant to a reactivity of thethermal addition polymerization reaction of the unsaturated hydrocarbongroup, since it is activated beforehand, the composition control of theobtained copolymer film is effectively carried out accompanied by achange in the supply ratio.

Henceforth, the organosiloxane copolymer film according to the presentinvention, by using the previously described characteristics, the filmconfiguration where the content ratio of the unit derived from firstorganosiloxane with cyclosiloxane backbone and the unit derived fromsecond orgnosiloxane with straight-chain siloxane backbone is changingin the film thickness direction can be readily produced. For example,when applying it as an insulation film used in producing semiconductordevice, at the upper and lower planes of the films, in the case ofmaking the layered structure by preparing other inorganic insulatingfilms, the composition of the copolymer film sandwiched between theinorganic insulating films at the interfaces near to the inorganicinsulating films contains much units derived from the secondorganosiloxane with straight-chain siloxane backbone as the maincomponent, so that the deposition property is enriched, and a highbridge density can bring about the composition indicating a highstrength. On the other hand, the composition inside the film contains arelatively high ratio of the unit derived from the first organosiloxanewith cyclosiloxane backbone, so that the density per volume isrelatively low, capable of suppressing the dielectric constant low. As aresult of this, the interfaces near to the inorganic insulating filmshave the high density, and although the dielectric constant isrelatively higher, as the whole copolymer film on average, which isworked out by taking an average with the interfaces and the film innersection, the effective dielectric constant can be low.

To make a good use of this advantage, the wiring layer embedding acopper film is prepared inside the copolymer film of the presentinvention, and since the dielectric constant of the copolymer film inbetween is suppressed low, the parasitic capacitance between wirings canbe controlled. In other words, according to the semiconductor device ofthe present invention, to make a layered structure by preparing otherinorganic insulating film at the upper and lower planes of the films,the deposition property at the interfaces with the inorganic insulatingfilms is set high, on the other hand, as the whole film, the effectivedielectric constant is set low. This way, the structure that preparesthe wiring layer embedding the copper film in the copolymer film isachieved, and the parasitic capacitance of the wiring layer issuppressed.

EMBODIMENTS

Hereunder, the embodiments of the present invention shall be explainedin more detail. The embodiment according to the present invention isonly one example, and should not be limited to the specific exampledescribed in the present invention.

First Embodiment

The organosiloxane copolymer film according to the present inventioncomprises a 4-membered cyclosiloxane composed of 4 silicon atoms and 4oxygen atoms shown in general formula (6) below, as one of the rawmaterials, and as one embodiment of the first organosiloxane monomerwith cyclosiloxane backbone.

General Formula (6): 4-Membered Cyclosiloxane Having a Plurality ofUnsaturated Hydrocarbon Groups.

In this formula, R11V, R12V, R13V, R1a, R21V, R22V, R23V, R2a, R31V,R32V, R33V, R3a, R41V, R42V, R43V, and R4a denote hydrocarbon groups,phenyl groups or hydrogen. Specifically,tetramethylvinyl-tetramethyl-cyclotetrasiloxane (TMVTMCTS) of chemicalformula (7), tetravinyl-tetramethyl-cyclotetrasiloxane (TVTMCTS) ofchemical formula (8), tetramethylvinyl-tetrahydro-cyclotetrasiloxane(TMVTHCTS) of chemical formula (9), andtetravinyl-tetrahydro-cyclotetrasiloxane (TVTHCTS) of chemical formula(10) are included in one of the examples of the first organosiloxanewith cyclosiloxane backbone, as shown in the general formula (6).

Chemical Formula (7): tetramethylvinyl-tetramethyl-cyclotetrasiloxane(TMVTMCTS)

Chemical Formula (8): tetravinyl-tetramethyl-cyclotetrasiloxane

Chemical Formula (9): tetramethylvinyl-tetrahydro-cyclotetrasiloxane(TMVTHCTS)

Chemical Formula (10): tetravinyl-tetrahydro-cyclotetrasiloxane(TVTHCTS)

Furthermore, the organosiloxane copolymer film according to the presentinvention uses 3-membered cyclosiloxane composed of 3 silicon atoms and3 oxygen atoms, as the first organosiloxane monomer with cyclosiloxanebackbone, as shown in general formula (11) below. In addition, thecyclosiloxane backbone can be 5-membered cyclosiloxane ofcyclopentasiloxane, 6-membered cyclosiloxane of cyclohexasiloxane orcyclosiloxanes having more members than that.

General Formula (11): 3-Membered Cyclosiloxane Having a Plurality ofUnsaturated Hydrocarbon Groups.

In this formula, R11V, R12V, R13V, R1a, R21V, R22V, R23V, R2a, R31V,R32V, and R33V denote hydrocarbon groups, phenyl groups or hydrogen.

According to the first organosiloxane monomer with cyclosiloxanebackbone, all the hydrocarbon groups bonded to the silicon atomsincluded in the cyclosiloxane backbone do not have to be unsaturated.Nevertheless, as the unsaturated hydrocarbon group to be bonded to thesilicon atom, it desirably includes the unsaturated hydrocarbon groupcapable of selective activation with a low energy electron in theplasma. The above example shows the organosiloxane having a molecularstructure where the silicon atom is directly bonded to the vinyl group,or bonded to C═C site of the unsaturated hydrocarbon group. Also, thesilicon atom of the organosiloxane can be bonded to, via the saturatedhydrocarbon chain, vinyl group (CH₂—CH—), ethinyl group (HC≡C—), andcyclobutenyl group. Furthermore, the hydrocarbon chain may include theunsaturated hydrocarbon group including a plurality of vinyl groups(CH₂—CH—) and ethinyl groups (HC≡C—).

To configure the organosiloxane copolymer, at least 2 or moreindependent sites capable of addition polymerization reaction arenecessary in the cyclosiloxane molecule, especially, for thecyclosiloxanes to be continuously connected via the unsaturatedhydrocarbon groups, at least 2 or more silicon atoms should be bonded tothe unsaturated hydrocarbon groups, in the cyclosiloxane. Furthermore,in forming the network structure of the organosiloxane copolymer film,among all silicon atoms configuring the cyclosiloxane, preferably 3 ormore silicon atoms are bonded to the unsaturated hydrocarbon groups.Especially, all silicon atoms configuring the cyclosiloxane shouldpreferably be bonded by at least one of the unsaturated hydrocarbongroup capable of addition polymerization, repsectively.

Second Embodiment

The organosiloxane copolymer film according to the present inventionuses the first organosiloxane monomer with cyclosiloxane backbone andthe second organosiloxane monomer with straight-chain siloxane backboneas raw materials. One embodiment of the second organosiloxane withstraight-chain siloxane backbone, is a straight-chain divinyl siloxanehaving a molecular structure where the terminal silicon atom of thestraight-chain siloxane shown in general formula (12) below is bondeddirectly to vinyl group (CH₂═CH—) or bonded to C═C site of theunsaturated hydrocarbon group.

General Formula (12): Divinyl Straight-Chain Siloxane

In the formula, R′1a, R′1b, R′11V, R′12V, R′13V, R′2a, R′2b, R′21V,R′22V, and R′23V denote hydrocarbon groups, phenyl groups, aliphatichydrocarbon groups, or hydrogen. Moreover, n denotes an integer of 1 ormore. Now, as examples of straight-chain divinyl siloxane having arepeating unit n=1 shown in general formula (12), aretetramethyldivinylsiloxane (TMVS) of general formula (13) anddimethyldiphenyldivinylsiloxane of general formula (14).

General Formula (13): tetramethyldivinylsiloxane

General Formula (14): dimethyldiphenyldivinylsiloxane

As another embodiment which is usable as the second organosiloxane,monovinylsiloxane shown in general formula (15) below where siliconatoms in the straight-chain siloxane are bonded to the unsaturatedhydrocarbon groups, and vinylsiloxane shown in general formula (16)below where all silicon atoms in the straight-chain siloxane are bondedto unsaturated hydrocarbon groups. Furthermore, divinylsiloxane whereall of the silicon atoms are bonded by 2 unsaturated hydrocarbon groupsare also included.

General Formula (15): Straight-Chain Monovinylsiloxane

In the formula, R′11V, R′21V, R′1b, R′2a, RV1a, RV1b, and R′2V denotehydrocarbon groups, phenyl groups or hydrogen, and n denotes an integerof 2 or more.

General Formula (16): Straight-Chain Divinylsiloxane

In the formula, R′11V, R′21V, R′1b, R′2a, RV1a, RV1b, RV2a, and RV2bdenote hydrocarbon groups, phenyl groups or hydrogen, and n denotes aninteger of 1 or more,

As another embodiment usable as the second organosiloxane includesvinyl-terminated monovinyl siloxane shown in general formula (17) belowwhere both the straight-chain siloxane and the terminal of a siliconatom are bonded to the unsaturated hydrocarbon group, and avinyl-terminated divinyl siloxane shown in general formula (18) below.

General Formula (17): Vinyl-Terminated Monovinyl Siloxane

In the formula, R′11V, R′12V, R′13V; RV1a, RV1b, R′1b, R′2a, R′2b,R′21V, R′22V, and R′23V denote hydrocarbon groups, phenyl groups andhydrogen, and n denotes an integer of 1 or more.

General Formula (18): Vinyl-Terminated Divinylsiloxane

In the formula, R′11V, R′12V, R′13V, RV1a, RV1b, R′1b, R′2a, RV1a, RV1b,R′21V, R′22V, and R′23V denote hydrocarbon groups, phenyl groups andhydrogen, and n denotes an integer of 1 and more.

Furthermore, in the second organosiloxane monomer with straight-chainsiloxane bankbone, the hydrocarbon group related to the additionpolymerization reaction can be aliphatic phenyl group or aliphatichydrocarbon group having a backbone capable of open-ring addition suchas cyclobutene or benzocyclobutene. Examples aremonobenzocyclobutene-monovinyl-terminated siloxane shown in generalformula (19) below, and bisbenzocyclobutene-terminated siloxane shown ingeneral formula (20) below, and bisvinyl-terminatedmethylbenzocyclobutenesiloxane shown in general formula (21) below.

General Formula (19): Monobenzocyclobutene-Monovinyl-Terminated Siloxane

In the formula, R′11 V, R′12V, R′13V, R′1a, R′1b, R′2a and R′2b denotehydrocarbon groups, phenyl groups, and hydrogen, and n denotes aninteger of 1 or more.

General Formula (20): Bisbenzocyclobutene-Terminated Siloxane

In the formula, R′1a, R′1b, R′2a, and R′2b denote hydrocarbon groups,phenyl groups, or hydrogen, and n denotes an integer of 1 or more.

General formula (21): bisdivinyl-terminatedmethylbenzocyclobutenesiloxane

In the formula, R′11V, R′12V, R′13V, R′21V, R′22V, and R′23V denotehydrocarbon groups, phenyl groups or hydrogen, and n denotes an integerof 1 or more.

Now, the examples of bisdivinyl-terminatedmethylbenzocyclobutenesiloxane having a repeating unit n=1, shown ingeneral formula (21), are bisvinyl-dibenzocyclobutene-dimethyl-siloxaneof chemical formula (22) andbismethylvinyl-dibenzocyclobutene-dimethyl-siloxane of chemical formula(23).

Chemical Formula (22): bisvinyl-dibenzocyclobutene-dimethyl-siloxane

Chemical formula (23):bismethylvinyl-dibenzocyclobutene-dimethyl-siloxane. In addition, thesecond organosiloxane monomer with straight-chain siloxane backbone, thehydrocarbon group related to the addition polymerization reaction can bevinylbenzocyclobutene structure shown in chemical formula (24) below. Asan example, bisvinylbenzocyclobutene-tetramethylsiloxane shown in thepreviously-described formula (1), furthermore,bisvenzocyclobutene-divinyldimethyldihydrosiloxane shown in chemicalformula (25) below, or bisbenzocyclobutene-divinyltetrahydrosiloxaneshown in chemical formula (26) below.

Chemical Formula (24): Vinylbenzocyclobutene Structure

Chemical Formula (1):bisvinylbenzocyclobutene-divinyltetramethylsiloxane

Chemical Formula (25):bisbenzocyclobutene-divinyldimethyldihydrosiloxane

Chemical Formula (26): bisbenzocyclobutene-divinyltetrahydrosiloxane

In above examples, those having the molecular structures where thesilicon atoms are directly bonded to vinyl groups or C═C site of theunsaturated hydrocarbon groups or aliphatic hydrocarbon groups havingthe backbone structure capable of open-ring addition such as cyclobuteneor benzocyclobutene are illustrated. The straight-chain organosiloxanemonomers having the structures where the silicon atoms are bonded to thevinyl (CH₂—CH—), ethinyl group (HC≡C—), and cyclobutenyl group, andbenzocyclobutenyl group, via the saturated hydrocarbon chain are alsoincluded. In other words, the straight-chain second organosiloxanemonomer having the straight-chain siloxane backbone usable in thepresent invention has at least a structure where the straight-chainsiloxane is bonded to the hydrocarbon group capable of additionpolymerization reaction, and preferably includes the straight-chainsiloxane where 2 or more hydrocarbon groups capable of additionpolymerization reaction independently. In addition, the secondorganosiloxane monomer having straight-chain siloxane backbonepreferably has 3 or more sites capable of addition polymerizationreaction. Furthermore, in the present invention, the “straight-chainsiloxane” in a broadest possible sense comprises all siloxanes exceptfor the cyclosiloxane. For example, the “chain siloxane” structureinteraction, the structure of which is connected by the hydrocarbonchain itself, is not included in the narrowly-defined “straight-chainsiloxane”, however, it can exhibit performance as “straight-chainsiloxane” possessed by the second organosiloxane monomer of the presentinvention. Accordingly, it is usable as the second organosiloxanemonomer having straight-chain siloxane backbone. Moreover, in thepresent invention, as the second organosiloxane monomer which is thestructural unit of the organosiloxane copolymer film, thepreviously-described mixture of the straight-chain siloxane can beutilized.

Third Embodiment

According to the third embodiment, as the first organosiloxane withcyclosiloxane backbone, tetramethylvinyl-tetrahydro-cyclotetrasiloxane(TVTMCTS) of chemical formula (8) is utilized, and as the secondorganosiloxane with stright-chain siloxane backbone,bisbenzocyclobutene-divinyltetramethylsiloxane of chemical formula (1)is utilized, for producing the organosiloxane copolymer film.

TVTMCTS (molecular weight=346) of chemical formula (8) has a structurewhere the methyl groups, and the vinyl groups as the unsaturatedhydrocarbon groups, are bonded respectively on each silicon atom on the4-membered cyclosiloxane backbone, and the material is a liquid at theroom temperature. On the other hand, BCBDVS (molecular weight=390) ofchemical formula (1) has a structure where benzocyclobutenyl group isbonded to the vinylene group (—CH═CH—) structure as the unsaturatedhydrocarbon group capable of addition polymerization, to each siliconatom terminal on the straight-chain siloxanc (—Si—O—Si—) backbone, andit is a liquid at the room temperature. In other words, both has atleast 2 of more unsaturated hydrocarbon groups, respectively.Specifically, the first organosiloxane has 4 unsaturated hydrocarbongroups capable of addition polymerization, and the second organosiloxanehas a total of 4 reaction sites in the unsaturated hydrocarbon groupscapable of addition polymerization. The TVTMCTS and BCBDVS accordinglyare separately vaporized, these are mixed beforehand, the mixed gas ispassed through the He plasma, and the vinyl group of TCTMCTS and thebenzocyclobutenyl group of BCBDVS are selectively volatilized.

As a result of this, according to the sites activated by the plasma, theaddition polymerization reaction progresses on the heated substrate, andthe open-ring addition type polymer formation shown in FIG. 6 takesplace. FIG. 6 shows schematically the polymerization reaction using theplasma excitation, for producing the organosiloxane copolymer film asone embodiment of the present invention, by using BCBDVS monomer gaswhich is a straight-chain siloxane, and by using TVTMCTS monomer gaswhich is a cyclosiloxane. In the drawing, R11V═H, R12V═H, R13V═H,R1a═CH₃, R21V═H, R22V═H, R23V═H, R2a═CH₃, R31V═H, R32V═H, R33V═H,R3a═CH₃, R41V═H, R42V═H, R42V═H, R43V═H, and R4a═CH₃. In other words,due to a low energy electron collision in the He plasma, accompanied bythe activation of benzocyclobutene structure, the cyclobutene ringsection causing the open-ring shown in chemical formula (2) and a vinylgroup (CH₂═CH—) forms the TVTMCTS and BCBDVS copolymers via the cycloring formation process performing the addition polycrmization reactionshown in chemical formula (3). Accordingly, the unsaturated hydrocarbongroup part included in the hydrocarbon group bonded to the siloxane, asa result of the selective activation, the addition polymerization iseasily generated, and the desired reaction path design is possible.

At this point, there's no means to carry out the time trend analysis ofthe strict reaction path during the copolymer film formation via theplasma excitation process. Nevertheless, FIG. 7 to FIG. 9 showschematically the reaction path of bridge structure formation in thecopolymer film including some estimates, and its time trend (side chainis not illustrated in some part).

FIG. 7 shows an example of the formation process of the organosiloxanecopolymer film, and the formation of network structure by polymerizationreaction of cyclosiloxane and straight-chain siloxane, accompanied bythe selective plasma excitation. FIG. 8 shows an example of theformation path of the organosiloxane copolymer film of the presentinvention, and shows the network structure formation by thepolymerization reaction of the cyclosiloxane and the straight-chainsiloxane accompanied by the selective plasma excitation, and shows thebridge formation after the straight-chain siloxane interaction. FIG. 9shows an example of the formation processing of the organosiloxanecopolymer, and shows schematically a network structure formation by thepolymerization reaction of the cyclosiloxane and the straight-chainsiloxane accompanied by the selective plasma excitation, and the2-dimensional bridge structure formation after the straight-chainsiloxane interaction.

First of all, along with the progress in the addition polymerizationreaction of the selectively activated sites by plasma, as shown in FIG.7, a large network structure organosiloxane copolymer film is formedwhereby the cyclosiloxanes are connected by the straight-chainsiloxanes. Furthermore, inside a BCBDVS unit of the copolymer film, theunreacted vinylene group (—CH═CH—) exists, and another BCBDVS generatesat the same time the addition polymerization of cyclobutene part insidethe benzocyclobutene structure in respect to the vinylene group(—CH═CH—) inside the BCBDVS unit. As a result of this, as shown in FIG.8, the bridge structure is further induced caused by the polymerizationreaction of BCBDVS unit interaction, which is a straight-chain siloxane.At this time, if the ratio of BCBDVS contained in the mixed gas is high,as shown in FIG. 9, more highly dense bridge structure is furtherinduced caused by the polymerization reaction of BCBDVS unitinteraction.

A network structure where the cyclosiloxane-derived units are dispersedis being formed inside the obtained copolymer film. Depending on theratio of BCBDVS included in the mixed gas, the organosiloxane copolymerfilm inducing additional bridge structure is grown on the heatedsubstrate caused by the polymerization reaction of BCBDVS unitinteraction further. Now, an existence ratio of the straight-chainsiloxane derived unit and the cyclosiloxane derived unit contained inthe copolymer film is determined by depending on mole ratios and supplyrates of the BCBDVS monomer gas and the TVTMCTS monomer gas contained inthe mixed gas. Moreover, the density of the obtained copolymer filmdepends on the mole ratios and supply rates of the BCBDVS monomer gasand the TVTMCTS monomer gas. The higher the content ratio of the BCBDVSderived unit which is a straight-chain siloxane, the higher the density.At this time, the siloxane unit density per unit area also increases,the deposition property is high, and the dielectric constant is alsohigh.

Next, the organosiloxane copolymer film formation process composed ofthe cyclosiloxane and straight-chain siloxane is described, which isobtained through the addition polymerization reaction of TVTMCTS andBCBDVS, using the deposition apparatus of the organosiloxane copolymerfilm shown in FIG. 3.

First of all, according to the initial state of the vaporizationcontroller, a vaporization controller valve 37, a valve 41 and a valve18 are opened. An exhaust pump 14 is used to form a vacuum inside thereaction chamber 1, an exhaust piping 16, a waste liquid piping 18, avaporization controller 34, and a vaporization raw material pipings 38.The vaporization temperature of the organosiloxane monomer inside thevaporization supplying system 61 is appropriately selected depending onthe saturated vaporization pressure necessary to maintain the desiredsupply amount. It is also important to select the vaporizationtemperature which is capable of maintaining the organic monomer partialpressure range, without causing the blockage due to an aggregation inthe middle of piping, and without the change in polymer quality or beingdecomposed during the piping process of vapor-supplying the organicmonomer. Moreover, the vaporization raw material supply pipings 38 areheated by beaters for preventing the aggregation inside the pipings sothat its component material should withstand heat. Alternatively, theorganic monomer partial pressure must be selected which is capable ofsetting the heating temperature within the heat resistance temperaturerange of the piping component material. Moreover, the heatingtemperature of the piping is monitored by the thermocouples being placedat various positions in the piping, which controls the piping heatingheater 3 for constantly setting the temperature. Next, a valve 45 isopened, and a carrier gas (He) 26 is supplied from a carrier gas supplypiping 40, to a vaporization controller 30 via a gas flow controller 31,which is further flown into the reaction chamber 1 via the vaporizationraw material supply pipings 38 and the valve 18, and exhausted outsideof the apparatus with an exhaust pump 14 via the exhaust piping 16. Inthe case of using the TVTMCTS and BCBDVS as raw materials, thevaporization temperature is set in the range of 170 degrees Celsius to210 degrees Celsius. On the other hand, the flow amount of He gas isselected in a range of 300 sccm to 500 sccm. Under the range ofpreviously-described conditions, the total pressure P of thevaporization controller 34 is in a range of 2 to 4 Torr. The totalpressure inside the reaction chamber 1 is 1.0 Torr. Moreover, a siliconsubstrate (semiconductor substrate) 5 for forming the semiconductorintegrate circuit can be heated to a range of 300 degrees Celsius to 400degrees Celsius by a substrate heating section 6 set inside the reactionchamber 1. Now, in the case of using the TVTMCTS monomer and BCBDVSmonomer, the substrate heating temperature is appropriately selected ina range of 200 degrees Celsius to 450 degrees Celsius.

According to the vaporization supply system 61 selecting thepreviously-described vaporization condition, the TVTMCTS monomer and theBCBDVS monomer are supplied to the reaction chamber 1 via the respectivevaporization raw material supply pipings, along with the He gas,respectively. The mixed gas composed of the TVTMCTS monomer gas and theBCBDVS monomer gas is homogenized at the shower head 7 section insidethe reaction chamber 1, and after that it is sprayed uniformlythroughout the whole substrate surface by the uniform flow distribution.

Below the shower head, under the state of not generating the He plasma,not much organosiloxane film is formed by spraying the mixed gas to theheated substrate. Accordingly, to the earthed substrate heating section,the RC power of 13.56 MHZ is applied to the shower head, and the Heplasma is generated under the shower head, and the raw materialorganosiloxane monomer is activated. In the activation process by thisplasma, preferably, the hydrocarbon groups (4-membered carbon ring andvinyl group) capable of addition polymerization which are respectivelypresent in the TVTMCTS monomer and the BCBDVS monomer are selectivelyactivated as much as possible. The RC power for generating plasma causedby the He carrier gas is selected in a range of 300 W to 100 W.

The mixed gas of the TVTMCTS monomer gas and the BCBDVS monomer gasreceive activation accordingly during a passage through the He plasma,by giving more thermal energy on the heated substrate surface, thecopolymerization reaction of the TVTMCTS monomer and the BCBDVS monomeris generated, and the organosiloxane copolymer film is formed. On theother hand, the unpolymerized monomer gas reaches a cooling trap 14which is cooled to about 20 degrees Celsius via the exhaust piping 16,and is aggregated inside the cooling trap 14 and collected so that itdoes not enter the exhaust pump 8.

As the total supply amount, after the pre-determined amounts of theTVTMCTS monomer gas and the BCBDVS monomer gas are vapor-supplied, firstof all, the RF power supply is stopped, the film growth is terminated,and after that, each monomer gas supply is stopped, and thesemiconductor substrate 5 remaining in the reaction chamber 1 is takenout.

FIG. 10 shows a structure of the organosiloxane copolymer film havingthe composition modulation in the thickness direction, preferably usedas an interlayer insulation film in the semiconductor device. As shownin FIG. 10, according to the processes above, during the film formation,a relative supply amount of the TVTMCTS monomer gas which is acyclosiloxane and the BCBDVS monomer gas which is a straight-chainsiloxane is changed. This way, the composition modulation typeorganosiloxane copolymer film with the content ratio of thestraight-chain siloxane derived unit and the cyclosiloxane derived unitchanging in the thickness direction is obtained. For example, in thestate of RF power of 100W, as for the mass flow rate conversion, theBCBDVS monomer gas only is supplied at a supply rate of 0.1 g/min(2.6×10⁻⁴ mol/min) for 10 seconds, and after that, while maintaining thesupply rate of the BCBDVS monomer constant, a supply rate of the TVTMCTSmonomer gas is increased to 0.08 g/min (2.6×10⁻⁴ mol/min) for 10seconds. The state of the TVTMCTS supply rate of 0.08 g/min and theBCBDVS supply rate 0.1 g/min is maintained for 20 seconds, then thesupply speed of TVTMCTS is decreased from 0.08 g/min to 0 g/min in 10seconds. After that, only the BCBDVS monomer gas is supplied at thesupply rate of 0.1 g/min for 10 seconds, and the RF power is terminated.

As a result of this, the BCBDVS film which is an intricatestraight-chain organosiloxane film of 50 nm thick is formed on aninterface layer of the silicon substrate heated to 350 degrees Celsius.75 nm thick part on top of it is a transition region of the increasingrelative content ratio of the cyclosiloxane derived unit against thestraight-chain siloxane derived unit, followed by the formation of theorganosiloxane copolymer film of approximately 1:1 content ratio of thestraight-chain siloxane derived unit and the cyclosiloxane derived unitof 200 nm thickness. Furthermore, on top of it is a transition regionwhere the content ratio of the cyclosiloxane derived unit is decreasingagainst the straight-chain siloxane derived unit, which is 75 nm thick.On the uppermost layer is coated with the BCBDVS film which is anintricate intricate straight-chain organosiloxane of 50 nm thickness.Now, in FIG. 10, a previously-described representative multilayerstructure comprised of an interface layer, a transition region, aconstant composition copolymer film, a transition region, and anuppermost layer is described. For this purpose, the three-layerincluding the interface layer, the constant composition copolymer film,and the uppermost layer is mentioned all having different structures.However, as described previously, the supply amounts of the monomers areindependently controlled, therefore, the copolymer film showingcontinuous structure change in the thickness direction is obtained bychanging the supply amount continuously. Moreover, in the transitionregion, it is possible to control to the form showing a suddenstructural change by changing the supply amount suddenly.

Now, the dielectric constant k of the sole BCBDVS film which is astraight-chain siloxanc is 2.6. The dielectric constant k of theorganosiloxane copolymer film of BCBDVS+TVTMCTS (1:1), as thestraight-chain siloxane and the cyclosiloxane, is 2.4. In the singleTVTMCTS film, the cyclosiloxane derived unit has a porous structure, andits dielectric constant k is ranging from 2.1 to 2.4, however, thesingle TVTMCTS film is lacking in the deposition property to theinorganic insulation film and the lower substrate. As it is, itsapplication to the multi-layer wiring is difficult. According to theFT-IR measurement, in the single BCBDVS layer film, a stretchingvibration of the straight-chain siloxane recognizes an adsorption peakof 1055 cm⁻¹. In the TVTMCTS/BCBDVS copolymer film, in addition to astretching vibration of the straight-chain siloxane of 1055 cm⁻¹, theadsorption peak of 1085 cm⁻¹ is recognized, which is caused bystretching vibration of the cyclosiloxane.

As illustrated above, according to the production method of theorganosiloxane copolymer film according to the present invention, aplurlaity of organosiloxane monomer gases are used as raw materials, andtheir supply amounts are independently and continuously controlledduring the formation, and the structure of organosiloxane film ischanged continuously in the thickness direction by changing the supplyamount ratio. Henceforth, as for the interfaces with other materials,the interface layers have the composition excellent in film mechanicalstrength and deposition property, and as a whole film, an effectivedielectric constant is low, and the composition modulation oforganosiloxane copolymer film is continuously formed. Furthermore, sincethe vaporized growth under low pressure is utilized, the organosiloxanemonomer mobility is large in the substrate surface, and theorganosiloxane copolymer film is obtained in which the cyclosiloxanederived unit and the straight-chain siloxane derived unit are evenlymixed at the molecular level, via the hydrocarbon chain, formed by theadditional polymerization.

Fourth Embodiment

FIG. 11 shows a case example of adopting the organosiloxane copolymerfilm produced utilizing the plasma excitation type additionpolymerization reaction of the present invention to the multilayerwiring of the MOSFET device. According to the semiconductor device shownin FIG. 11, the TVTMCTS/BCBDVS organosiloxane copolymer film mentionedin the third embodiment is adpoted as 3 wiring insulation layers ofcopper wirings 85, 87 and 89 (M1, M2 and M3) on the MOSFET 82 formed onthe silicon substrate 81. The first copper wiring layer (M1) 85 isformed on a tangstan compact plug 83 formed inside the inorganicinterlayer insulation film 84 on the MOSFET 82. On the surface of theinorganic interlayer insulation film 84, as a copper spreading barriergap film, an extremely thin film carbon-containing silicon nitrate film(SiCN) of less than 10 nm is formed.

The wiring insulation film 91 of the first copper wiring layer 85 hasthe 3-layer structure including: an organosiloxane film 91 a consistingof the straight-chain siloxane that only uses the BCBDVS of the secondorganosiloxane monomer; an organosiloxane copolymer film 91 b consistingof the cyclosiloxane and the straight-chain siloxane that use both theBCBDVS mentioned above and TVTMCTS of the first organosiloane monomerwith cyclosiloxane backbone; and an organosiloxane film 91 c consistingof the straight-chain siloxane that only uses the BCBDVS. In otherwords, a continuously-formed composition modulation type organosiloxanecopolymer film 91 comprises the BCBDVS films 91 a and 91 c excellent inthe mechanical strength and the deposition property that are placed asthe interface layers of the lower base and upper layer. The BCBDVS filmwith the dielectric constant k=2.5 to 2.7 include 1 straight-chainsiloxane group (—Si—O—Si—) per unit backbone. The straight-chainsiloxane comprises a complex bridge structure via the benzocyclohexanering created by the addition polymerization, as a result, the film isexcellent in mechanical strength and excellent in the depositionproperty with the copper spreading barrier film. On the other hand, theTVTMCTS/BCBDVS organosiloxane copolymer film 91 b of the intermediatelayer being continuously formed, has a structure forming a complexbridge of the straight-chain siloxane backbone via the benzocyclohexanering or hydrocarbon chain, in respect to the cyclosiloxane backbonehaving pores. Within the intermediate layer, due to a presence of thepores caused by the cyclosiloxane backbone, the whole film is porous,and its effective dielectric constant k, given that the content ratio ofthe TVTMCTS/BCBDVS is 1:1, is about k=2.4.

The effective dielectric constant of the composition modulation typeorganosiloxane copolymer film used in the wiring insulation film 91 forthe first copper wiring layer 85 accordingly depends on the filmthickness ratio of the BCBDVS/TVTMCTS film 91 b of the intermediatelayer and the BCBDVS films 91 a and 91 c of the interface layers,therefore, the total thickness of the BCBDVS films 91 a and 91 c of theinterface layers are ideally 20% the thickness of the BCBDVS/TVTMVTSfilm 91 b of the intermediate layer. For example, in the case of thecopper wiring 85 having the thickness of 300 nm, and provided that thethickness of the BCBDVS film 91 a, the BCBDVS/TVTMVTS film 91 b, and theBCBDVS film 91 c are 15 nm/270 mm/15 nm, respectively, the effectivedielectric constant of the wiring insulation film 91 is about 2.5.

The composition modulation type organosiloxane copolymer film used forthe wiring insulation film 91 is grown using the deposition apparatusshown in FIG. 3. Herewith, the substrate heating temperature is 350degrees Celsius, and the frequency of 13.56 MHz and the RF electricpower of 100 W are applied to the shower head, and the He plasma isgenerated by using the He carrier gas. At first, in the initial stage ofthe film formation, the BCBDVS monomer only is supplied, and the BCBDVSfilm of 15 nm thickness is grown. After that, to attain an equivalentmole supply ratio of the BCBDVS monomer and the TVTMCTS monomer, forexample, the BCBDVS monomer supply rate of 0.1 g/min, and the TVTMCTSmonomer supply rate of 0.08/min are supplied, and the BCBDVS/TVTMCTSorganosiloxane copolymer film of 270 nm thickness is grown. After that,again, the BCBDVS monomer only is supplied, and the BCBDVS film of 15 nmthickness is grown. Now, the supply amount of the BCBDVS monomer is setconstant, and the supply amount of the TVTMCTS is continuously reduced,and the BCBDVS/TVTMCTS copolymer film with changing composition in thewhole layer is formed. At this time, the film configuration has a highconcentration of the siloxane group in the vicinity of the interfaceswith the upper layer and the lower base, and has a gradually decreasingconcentration in the intermediate layer. In the wiring gutter formed inthe first wiring interlayer insulation film, after coating its side andbase by TaN barrier film of 10 nm thickness, and the first singledamocene copper wire layer 85 is formed inside the gutter.

After that, the copper spreading barrier film 90 of 10 nm thickness isgrown on the first copper wiring layer. Example of the copper spreadingbarrier film is SiCN film of the dielectric constant ranging from 3.0 to3.5 grown by emitting a silan gas (SiH₄) for 3 seconds, thebistrimethyl-silyl-carbodiimido of chemical formula (27) is vaporized,which is induced into the plasma composed of He/NH₃ mixed gas or He/N₂mixed gas, and which is grown on the substrate heated to 250 degreesCelsius to 350 degrees Celsius coating the first copper wiring layer.The RF power used in generating the plasma is about 100 W.

Chemical Formula (27): bistrimethyl-silyl-carbodiimido

The SiCN film can also be formed by inducing a trimethylsilane((CH₃)3SiH) into a plasma consisting of He/NH₃ mixed gas. The dielectricconstant k of the SiCN obtained by this method is normally larger than aSiCN film using the bistrimethyl-silyl-carbodiimido as a raw material,which is k=3.0 to 3.5.

After that, a via insulation film 92V is grown on the copper spreadingbarrier film 90. As the via insulation film 92V, a silicon oxide filmproduced in a plasma CVD using a silane gas, which is excellent in themechanical strength, or an amorphous SiOCH film obtained by, forexample, decomposing a paramethyl-dimethoxy silane gas (PM-DMOS) ofchemical formula (28) below, which is a sole organic siloxane notincluding the unsaturated hydrocarbon chain, are used. As required,after accumulation of the via insulation film 92V, its surface layer isflattened by scraping off by using the chemical mechanical polishingmethod.

Chemical Formula (28): paramethyl-dimethoxy Silane

After that, the second wiring insulation films 92 a, b, and c are grown.Herewith, as the second wiring insulation films 92 a, b, and c, the3-layer structure film including a BCBDVS film 92 a, a BCBDVS/TVTMCTSorganosiloxane copolymer film 92 b, and a BCBDVS film 92 c areconsecutively grown, by using the method illustrated in the thirdembodiment. Laminated hard mask (not illustrated) of SiCN/SiO₂ is usedto form the wiring gutters to the wiring insulation film 92 a, b, and c.Furthermore, a via is formed to the via insulation film 92V. As theetching gas, the C₄F₈/N₂/O₂ system gas is used accordingly. After that,by using ionization sputtering method, a Ta/TaN or a TiW/TiWN laminatedbarrier film (75 nm/75 nm) is grown, furthermore, copper seed film of1000 angstrom is grown. On the Cu seed film, a Cu film of 7000 angstromis grown by using the electrolysis plating method, annealed at 300degrees Celsius for 30 minutes, and then the grain growth of the Cuplated film is carried out. A barrier metal consisting of TiWN or Ta/TaNand Cu film, which are present at surface other than the via and thewiring gutter section is removed by the chemical mechanical polishingmethod, and the wiring structure embedding a copper in the via 86 andthe wiring gutter 87 are formed as one. The second copper wiring layer92 is formed according to the series of processes accordingly. Byrepeating the same processing, the multi-layer wirings using theorganosiloxane copolymer film is formed as the interlayer insulationfilm on a transistor 82 of the silicon semiconductor substrate, in whichthe cyclosiloxane derived units and the straight-chain siloxane derivedunits undergo addition polymerization to be connected by the hydrocarbonchains.

Henceforth, by using the growth method of the organosiloxane copolymerfilm according to the present invention, as for the vaporizationreaction system where the organosiloxane copolymer film is formed, forexample, from the BCBDVS monomer which is one embodiment of thestraight-chain siloxane and the TVTMCTS monomer which is one embodimentof the cyclosiloxane as raw materials, the respective content ratio ofthe siloxane backbone derived units can be changed from 0% to 100%.Accordingly, as for the wiring interlayer insulation films of eachwiring layer such as LSI multi-layer wirings, if the required physicalproperties of the film differ, for example, the mechanical strength, thedeposition property or the dielectric constant, by controlling thesupply rates of the plural kinds of organosiloxane monomer gases as rawmaterials, the property of the obtained copolymer film is changed.

In the illustrated growth example of the copolymer film, the BCBDVS isused as the straight-chain siloxane, and the TVTMCTS is used as thecyclosiloxane, however, the characteristic point of the presentinvention lies in mixing the plurality of straight-chain siloxanemonomer gases and the cyclosiloxane monomer gases, and the vaporizationgrowth of the orgaonsiloxane copolymer film having the desiredcomposition is possible. For example, among the various cyclosiloxanesmentioned in the first embodiment and various straight-chain siloxanesmentioned in the second embodiment, a plurality of organosiloxanes areselected as required and mixed, and the organosiloxane copolymer filmhaving the composition corresponding to their supply ratios can bevaporized and grown. Furthermore, in addition to the mixed gas of 2 ormore organosiloxane monomers capable of self polymerization,furthermore, a polymer auxiliary gases such as acetylene or ethylene,trivinylsilane, and divinylsilane are added, to carry out thevaporization growth of the organosiloxane film including the auxiliarycopolymer unit.

Fifth Embodiment

In the fifth embodiment, the 3-membered cyclosiloxane group shown ingeneral formula (11) above as the first organosiloxane havingcyclosiloxane backbone is used, and the divinylsiloxane group shown ingeneral formula (12) above as the second organosiloxane havingstraight-chain backbone is used, to form the copolymer film. FIG. 12shows the polymerization reaction using the plasma excitation in formingthe organosiloxane copolymer film which is one embodiment of the presentinvention by using the divinylsiloxanes group shown in general formula(12) as the straight-chain siloxane and the 3-membered cyclosiloxanesgroups shown in general formula (11) as the cyclosiloxane. FIG. 13 showsa formation of the hexagonal lattice network structure by thepolymerization reaction of the divinylsiloxane group and the 3-memberedsiloxane group, accompanied by the selective plasma excitation which isan example of the formation processing of the organosiloxane copolymerfilm. Under the combination of these raw materials, the organosiloxanecopolymer film obtained at the polymer condition using thepreviously-described plasma excitation, the additional polymerizationreaction occurs in between the unsaturated hydrocarbon group on siliconatom of the 3-membered cyclosiloxane group and unsaturated hydrocarbongroup of the divinylsiloxane group terminal shown in FIG. 12. As shownin FIG. 13, the copolymer film has a hexagonal lattice as basic filmconfiguration, in which the 3-membered cyclosiloxane backbone derivedfrom the 3-membered cyclosiloxane groups as the lattice points which areconnected in between by the divinylsiloxane group derived bridge chain.Now, by using a mixture of the 3-membered cyclosiloxane and the4-membered cyclosiloxane as the first organosiloxane havingcyclosiloxane backbone, the organosiloxane copolymer film having anetwork structure where the hexagonal lattice and square lattice areintermixed, is grown on the semiconductor substrate.

INDUSTRIAL APPLICABILITY

The organosiloxane copolymer film according to the present invention, bymixing in plural as raw materials the first organosiloxane gas withcyclosiloxane backbone and the second siloxane gas with straight-chainbackbone, the organosiloxane copolymer film can be vaporized and grown,including the network structure formed by the cyclosiloxane derived unitand the straight-chain siloxane derived unit. Furthermore, theseorganosiloxanes are vaporized, and while controlling their supplyamounts independently, and while changing the supply ratio of the mixedgas, it is supplied to the reaction chamber, so that the configurationratio of the cyclosiloxane and the straight-chain siloxane is changingin the growth thickness direction, and the organosiloxane copolymer filmis obtained. Moreover, in the obtained organosiloxane copolymer film,its cyclosiloxane backbone included has pores surrounded by thesiloxanes, and the pores become a structural body incorporating thenetwork structure consisting of the straight-chain siloxanes. The sizeof pores surrounding the siloxane is determined by controlling thenumber of membered rings of the cyclosiloxane which is a raw material.Moreover, the pore density has an advantage of being able to becontrolled by changing the gas mixture ratio with the firstorganosiloxane and the second organosiloxane supplied as the rawmaterials. Using this advantage, at the interfaces contacting theinorganic insulation film of the lower base and the inorganic insulationfilm of the upper layer, an organosiloxane copolymer film including manystraight-chain siloxanes with the excellent mechanical strength anddeposition property is positioned, and at the intermediate layer sectionpositioned in between the upper and lower interfaces, an organosiloxanecopolymer film including many cyclosiloxane derived units having a smallbulk density is positioned. As a whole film, on average, the effectivedielectric constant at the interfaces and the intermediate layer is low.At the same time, the interlayer insulation films having the excellentmechanical strength and deposition property at the upper and lowerinterfaces are obtained.

1. An organosiloxane copolymer film having plural kinds oforganosiloxane derived composition units, wherein the plural kinds oforganosiloxane derived composition units comprises at least a firstorganosiloxane with a cyclosiloxane backbone derived unit and a secondorganosiloxane with a straight-chain siloxane backbone derived unit;wherein the organosiloxane copolymer film forms a bridge structure bybonding a plurality of second organosiloxanes to the firstorganosiloxane; and wherein the copolymer film has a film configurationin which a content ratio of the first orgonosiloxane backbone derivedunit and the second organosiloxane with a straight-chain siloxanebackbone derived unit is changing in the film thickness direction.
 2. Anorganosiloxane copolymer film according to claim 1, wherein thecopolymer film is configured so that an upper and a lower planes of thecopolymer film in the thickness direction are both contacting aninorganic insulation film, wherein the content ratio of the secondorganosiloxane derived unit is higher in the vicinity of an interfacewith the inorganic insulation film at both the upper plane and lowerplane, than the content ratio of the second organosiloxane derived unitat an inner portion of the copolymer film; and wherein a density of thecopolymer film in the vicinity of the interface is larger than a densityof the copolymer film in the inner portion of the copolymer film.
 3. Asemiconductor device comprising art interlayer insulation filmconsisting of an organosiloxane film, wherein the organosiloxane film isan organosiloxane copolymer film having plural kinds of organosiloxanederived composition units; wherein the plural kinds of organosiloxanederived composition units comprises at least beth a first organosiloxanewith a cyclosiloxane backbone derived unit and a second organosiloxanewith a straight-chain siloxane backbone derived unit; wherein a bridgestructure is formed by bonding a plurality of second organosiloxanes tothe first organosiloxane; wherein the organosiloxane copolymer film issandwiched by inorganic insulators; wherein the content ratio of thesecond organosiloxane derived unit is higher in the vicinity of aninterface with an inorganic insulation film at both an upper and a lowerplanes, the content ratio of the second organosiloxane derived unit atan inner portion of the copolymer film; and wherein a wiring layer isformed within the organosiloxane copolymer film embedding a copper filmtherein.
 4. A vapor deposition method for depositing an organosiloxanecopolymer film having plural kinds of organosiloxane derived compositionunits on a substrate, wherein the plural kinds of organosiloxane derivedcomposition units comprise at least a first organosiloxane with acyclosiloxane backbone derived unit and a second organosiloxane with astraight-chain siloxane backbone derived unit and wherein theorganosiloxane copolymer film forms a bridge structure by bonding aplurality of second organosiloxanes to the first organosiloxane, whereinthe method comprises the steps of; vaporizing a first organosiloxanemonomer with cyclosiloxane backbone; vaporizing a second organosiloxanemonomer with straight-chain siloxane backbone; supplying a vaporizedfirst organosiloxane monomer gas at a predetermined supply rate;supplying a vaporized second organosiloxane monomer gas at apredetermined supply rate; forming a mixed gas by mixing the suppliedfirst organosiloxane monomer gas and the supplied second organosiloxanemonomer gas; introducing the mixed gas in a reaction chamber underreduced pressure; and spraying the introduced mixed gas onto a heatedsubstrate after passing through a plasma atmosphere generated in thereaction chamber, wherein the vapor deposition method grows a copolymerfilm forming a bridge structure by reacting the first organosiloxanemonomer and the second organosiloxane monomer in the mixed gas sprayedonto the substrate, and thereby bonding a plurality of secondorganosiloxanes to the first organosiloxane.
 5. A vapor depositionmethod according to claim 4, wherein a supply rate ratio of the firstorganosiloxane monomer gas and the second organosiloxane monomer gas ischanged by changing supply rates of the first organosiloxane monomer gasand the second organosiloxane monomer gas respectively, and thereby inresponse to the change of the supply rate ratio, a content ratio of thefirst organosiloxane derived unit and the second organosiloxane derivedunit is changing in the film thickness direction.
 6. The organosiloxanecopolymer film according to claim 1, wherein the bridge structure isformed by bonding in plural the first organosiloxane and the secondorganosiloxane via an organic group.